Plants and plant by-products are now gaining attractiveness in treatment of bacterial infections and food preservation. The objective of this study was to assess antibacterial activity of some Egyptian plant and plant by-products against the locally pathogenic isolates from patients having infectious diseases in our country. Screening of antibacterial activity of ethanol, methanol and hexane extracts of some plants: grape leaves (Vitis vinifera), mulberry leaves (Morus alba), mallow leaves (Corchorus olitorius) and lemon leaves (Citrus limon) toward Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella sp., were investigated. Antibacterial activity was performed by the agar disc diffusion method. The ethanol and methanol extract of tested plant leaves showed promising antibacterial activities against both Gram-positive and Gram-negative tested bacterial isolates due to its great ability to extract those polyphenolic and biological active compounds from natural sources which effectively act against broad spectrum bacteria. Ethanol followed by methanol were found to be the best solvents of choice to extract natural products to get maximum health and medicinal benefits. The results revealed that the extraction efficiency increase with polarity increasing of the solvents, hence the highest extraction done with ethanol and methanol and the lowest extraction with nonpolar solvent n-hexanedid not exhibit any activity against all the tested bacteria. Irradiation at 5 and 10 kGy did not significantly affect the antibacterial activity of all tested plant leaves. Results indicate the potential of these plants for further work on isolation and characterization of the active compounds responsible for antibacterial activity and its exploitation as therapeutic agents